Here is some info on this game from RPGFan:

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Taito will release Ys IV Mask of the Sun: A New Theory for PlayStation 2 in Japan in late May. The remake of the classic 1993 action RPG will feature 3D environments. Compared to the original version, the game's scenario and system will get a complete make-over. Taito also plans to enhance the story by offering a more complete version of Adol Christian's fourth adventure. Furthermore, a new Element system, based on the Holy Sword which players obtain in the game, will be introduced.

Ys IV Mask of the Sun: A New Theory for PlayStation 2 will be available in Japan on May 26th for 5,800 yen ($55.39 US). Ys IV will be the third installment of Nihon Falcom's flagship series to be released in Japan this year, as Ys VI: The Ark of Napishtim for PlayStation 2 and PlayStation Portable as well as Ys III: Wanderers from Ys are both scheduled to be available later this month.